In the separation of components of a gas or vapor mixture by mass, especially in isotope separations such as the separation of uranium isotopes, it is known to transform the element whose isotopes are to be separated into a gas phase and to effect the separation by the preferential enrichment of the gas stream in the compounds of one of the isotopes, thereby separating to a greater or lesser extent compounds of two or more isotopes from one another.
In the case of uranium, for example, the uranium can be converted to the uranium hexafluoride, which is in a gas or vapor form and a gas stream containing mixtures of uranium hexafluorides of the uranium isotopes can be fed at high velocity through a slot-like nozzle to produce jets from which a portion of the fluid stream is peeled off or skimmed to enrich one of the fluid portions with the relatively heavier compounds of the uranium isotope of greater mass and the other fluid portion in the uranium isotopes of the lighter mass.
Such methods are used for U.sup.235 enrichment, the component which preferentially contains the U.sup.235 gaseous compounds being repeatedly subjected to such separation in a multiplicity of stages until the desired degree of enrichment is obtained.
The jet may be deflected along a curved path which results in a certain degree of separation within the stream of the heavy and light components and a stratification of these components within the stream so that, when the skimming or peel-off baffle intercepts only a portion of this stream, the two components into which this baffle separates the stream are relatively enriched in the heavier and lighter components.
For this type of separation, a passage-forming unit can be provided which has a substantially rectangular plane and cross-sectional configuration, i.e. can be generally in the form of a rectangular parallelepiped, with the passage being separated by partitions along which nozzle-forming cleats or strips are provided on one side to cooperate with curved flow-deflecting portions and peel-off strips forming skimming baffles which deflect the skimmed portion of the stream into the adjoining passage.
The nozzle-forming strips or cleats and the peel-off strips or cleats can have portions reaching into the flow-deflecting groove to form a discharge gap for the nonskimmed portion of the fluid between them.
The nozzle-forming edge of the nozzle strip defines with the curved wall of the flow-deflecting groove a slot-like constriction which constitutes the actual nozzle which accelarates the flow along the wall of the groove, a portion of the flow being intercepted by the edge of the peel-off baffle extending into the groove to recover the heavy component whereas the light fraction is discharged through the gap between the strips.
The passage-forming unit thus has alternating passages for the gas mixture to be separated and for the recovered heavy fraction.
Systems of this type function efficiently and effectively when the requisite geometry is ensured by precision fabrication and minimal tolerances. It has been found to be necessary to maintain tolerances of 0.01 mm and less for optimum operation (see German Pat. No. 24 19 192, column 2, lines 32 through 41).
In an earlier system operating under these principles (see German Pat. No. 11 98 328, FIGS. 3 and 4) the passage-forming partitions of the unit are independent structural elements held in place by end plates which simultaneously form corresponding inlet and outlet openings for the gas or vapor mixture to be separated and the recovered heavy phase.
The strips forming the nozzle edges and the peel-off strips are covers closing the passages.
As a result, the structure has numerous parts and it is difficult to maintain the narrow tolerances required for effective operation. From a practical point of view, moreover, it is difficult to maintain the required tolerances at a reasonable cost. During fabrication various uncontrolled errors can be introduced which are additive upon assembly of the apparatus and derive not only from the difficulty in fabricating a multiplicity of identical components but also from the greater difficulty of mounting, affixing or securing numerous elements in precisely the same manner in the unit.